The nervousness of Nairobi's booksellers strikes me as exaggerated, a throwback to another era. The government has not banned the book and there's been no mention of libel suits. That's probably because those involved in Anglo Leasing have had their role exposed in the Kenyan and international press so many times before, they know there's no point. But I think this self-censorship shows how little things have moved on from the bad old Moi era. The scars from that bullying clearly go very deep.

While this bout of self-censorship lasts, my practical advice to any Kenyans who want to read the book is: buy it on www.amazon.co.uk or, if you have friends or family living abroad, ask them to bring a copy over when they next return. In this day and age, the flow of information really can't be stopped. I'm sure Nairobi's booksellers will pluck up their courage as they gradually register there are no repercussions. In the meantime, they're missing a great business opportunity.

What inspired you to write an entire book just about John Githongo and the corruption in Kenya? There are a number of others who since independence have taken similar positions, even in Githongo's era there were people such as Maina Kiai who stayed on and fought. Why is Githongo so special to you and the West in general?

In my book, I explicitly pay tribute to the work of people like Maina Kiai, Mwalimu Mati, Gladwell Otieno, Lisa Karanja, Ory Okolloh and a host of human rights activists, journalists and bloggers. I'm well aware that John Githongo was not waging that battle on his own. But from a writer's perspective, his story was the obvious one to tell. No other anti-corruption campaigner was welcomed into State House's inner sanctum or came to be a presidential confidant, and no one else took such dramatic, provocative action on learning the truth. John's upbringing, his Kikuyu identity, his family connections also meant the dilemma he faced was highly personal and incredibly stark. His story encapsulates the struggle between two conflicting philosophies, world views, and generations, making it a perfect way of exploring modern Kenya's predicament.

In a recent article for the Independent you wrote that many Kenyans experience a spasm of irritation when they hear outsiders mention Githongo. In light of this do you think sales of your book will do well in Kenya?

I have a certain sympathy with Kenyans who criticize Westerners for fixating on symbolic individuals, ignoring the dogged work done by less high-profile players and organizations. We do tend to do that, but then, Africa, with its history of charismatic Big Men leaders and weak institutions, is a continent where individuals often do play a disproportionately important role. What John did was obviously hugely controversial. But yes, I expect the book to sell well, even amongst those who are furious with him. Every intelligent Kenyan is currently trying to work out where the country went wrong, why it is in such terrible trouble, and whether one admires John Githongo or reviles him, his story sheds fascinating light on today's crisis.

How much cooperation did Githongo, his family and his friends give you in writing the book?

I once totted up the number of full-length interviews I'd had with John Githongo, the lunches, the dinners, and the long chats in airport lounges, and it came to well over 20. That sounds like quite a lot, but as a book writer, you always want more, because you hope to get under your subject's skin, discover the real man behind the public persona, while the subject of a biography tends to become very wary of their privacy being invaded and increasingly tries to avoid that scrutiny.

I interviewed most, but not all, the members of John's immediate family, met his parents several times, and as many friends and colleagues as I could. There comes a point where you have to decide: OK, that's it, I know what I know, now it's time to start writing.

Would you know if Githongo plans his own book on the whole Anglo-Leasing mess or even an autobiography?

There's been talk of a John Githongo book ever since he went into exile. But you'll have to ask him about that – I don't know what the situation is.

How much did you have to cut out because of libel?

I got to know my publisher's lawyers rather well in the run up to publication! They drew up a very detailed legal report and we spent several long days going through it, point by point, making sure we could back up every allegation. It was a pretty draining process, because the stakes were so high. But I was helped enormously by John Githongo's personal idiosyncracies and daily habits. He's a compulsive diary-keeper, a man who has recorded every conversation and significant encounter since he was in his teens, who never goes anywhere without his little black notebook. Once he became anti-corruption czar, there were the taped conversations and the collected documents to add to that. This kind of detailed logging makes lawyers very happy, it's exactly what they want. So while I certainly was forced to cut some material, it was not as much as I had originally feared.

What is your view on the SFO dropping its A-L investigation?

The announcement that the Serious Fraud Office had abandoned its investigation because of the lack of government cooperation was no surprise. It's been clear for many years that the judicial system is part of the problem in Kenya today, impunity the rule, and that the bodies originally set up to combat top-level sleaze, like the Kenya Anti Corruption Commission, serve instead as protective walls behind which Kenya's looters shelter. One of the things my book records is the number of times Justice Aaron Ringera advised John to stop investigating Anglo Leasing and discouraged him from returning to Kenya to testify. I was delighted to hear UN rapporteur Philip Alston calling for the sacking of Amos Wako recently. As long as men like Wako and Ringera remain in office in Kenya, top-level corruption will thrive.

But we Brits also have nothing to be proud of. Our government signs international anti-corruption conventions and promises to crack down on the bribing by British companies abroad. Then, as soon as it looks likely that the SFO is about to uncover major corruption perpetrated by a British company – BAE – the investigation is dropped. If the British government behaves like this, it shouldn't be surprised when African countries like Kenya take exactly the same cynical approach. I'm ashamed of my own government's hypocritical record on corruption.

What is your reaction to government ignoring the book's publication?

Well, what could Kibaki and his ministers actually say? John Githongo was there, no one was better placed, professionally speaking, to understand the workings of Anglo Leasing, he collected the evidence and his story has never wavered. It's going to be either a very rash or very stupid man who tries to challenge that account. I can therefore see why they might choose, to stay silent.

But I think there's also another, more depressing factor behind this silence. Journalist Kwamchetsi Makokha recently pointed out in a column that Anglo Leasing is now something Kenyan politicians joke about. The political class has discovered, in the wake of Goldenberg and a host of other scandals, that you can be caught with your hand in the till and nothing actually happens. No prosecution, no arrest, no obligation, even, to return the stolen money and if you lose your job, it's only temporary. I'm sure those who perpetrated Anglo Leasing are telling themselves: "So, let this mzungu talk. Who cares about that book? This will pass, and it won't stop us stealing." The perpetrators are so sure of themselves, they can't even be bothered to protest their innocence.

You have also written about Congo and Eritrea. How would you rank corruption in Kenya compared to the rest of Africa?

I interviewed a Kenyan secretary the other day and she calculated she paid between one and five bribes a week. That's well over 200 a year. If her experience is typical, then petty corruption is actually worse now than it was under Moi. And that's only one side of the equation, of course. Since the coalition government was formed, we've had the scandals over the sale of the Grand Regency, maize supplies and petroleum deliveries, which all reach up to cabinet level. It seems that Kenya is in the grips of a top-level looting frenzy. The last Transparency International Corruption Perceptions Index placed it at 147th on a list of 180 countries – which seems about right to me.

First seen in the Nairobi Star. Thanks to William Mwangi, Michela Wrong and the Nairobi Star for covering these documents.